trim problems?

I will start by saying i am sorry if i mis-categorized this thread but read on and let me know what you guys think:

I have a 79 wellcraft sunhatch with 198(5.0) gm mercruiser engine with matching MC-1 drive, everything appears to be original to the boat. With that being said i am having issues with my trim system and dont know where to start.
1.)i know the motor needs a solenoid as one post is broke out
2.)i can lift it by hand without much force and it wont stay up
3.)i have no visible fluid leaks and when i bought the boat i was able to trim all the way up by using a starter solenoid off a ford truck and it stayed up until i got it home , after 2 or three days its was all the way in the down posistion and is acting as described above

-do i look for leaks? do i get new cylinders (i know that there is no way of telling if something is broke inside the cylinders without disassembly) or do i go for broke and try to upgrade my trimp system all together with a newer model set up (if at all possible without heavy modifications?)

thank you all for reading and again to the moderators i just didnt knjow where to place my thread as it does pertain to my drive and is mercruiser?

-Jim

Re: trim problems?

any help is welcome or any corrections to my theories and how to troubleshoot ... i know youre all busy with youre own issues im just hoping to get some experienced know how on what to do, where to buy parts etc what parts to buy thanks

Re: trim problems?

Is your trim pump full of oil? That would be the first thing to check. If there is no oil, fill it up , run it and see what happens.

10W30 engine oil is what Mercruiser used in those pumps.

Re: trim problems?

Don S said:

Is your trim pump full of oil? That would be the first thing to check. If there is no oil, fill it up , run it and see what happens.

10W30 engine oil is what Mercruiser used in those pumps.

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don you are all knowing! filled it with motor oil and now i can get it to stay in posistion , i just need to buy the proper solenoid for it so i can trim up and down normally right now i can only trim up with how i have it rigged but im hopeful that by replacing that and cleaning up the wiring mess i should have full function back with my trim system

-**to any people new to this forum LISTEN TO THESE GUYS! they know what theyre talking about this is the 3rd of a series of sever mechanical issues that theyve helped guide me in the proper direction to save hundreds in labor , boating isnt cheap but they make life a tad easier especially in the wallet